Various groups are working to develop an electron-beam direct-write lithography tool technology that uses multiple electron beams rather than the present state-of-the-art, which uses only a single electron beam. This would allow very high resolution lithography made possible with direct-write e-beam lithography, but at higher speeds than are possible with a single electron beam in the present direct-write e-beam systems.
Electron beam lithography has some distinct advantages for resolving extremely small feature sizes since the wavelength of an electron beam is small compared to that of optical frequencies. Currently, single electron beam lithography is capable of resolving feature sizes down to approximately 10 nanometers and therefore exceeds the resolution of any currently used photolithography platform in the semiconductor manufacturing industry.
However, current electron-beam lithography systems can write using only a single electron-beam and the time required to write large and complicated patterns on the substrate surfaces is exceedingly long compared to conventional photolithography thereby making e-beam lithography too costly for most production applications.
However, if a multiplicity of electron-beams is used simultaneously to direct write patterns, then the scan rates and substrate through-puts are increased accordingly and e-beam lithography becomes much more attractive for production applications.
Multiple electron-beam (e-beam) direct-write lithography tools are capable of performing lithography at the 45 nanometer node with the potential of scaling the resolved features sizes down to the 32 nanometer node and beyond (i.e., 22 nanometer node, 16 nanometer node, 11 nanometer node), possibly capable of resolving features to below that of the level of current e-beam lithographic systems of around 10 nanometers.
A key benefit of this tool is the capability to allow the production of small lots of wafers while using state-of-the-art fabrication technologies, at low-cost and with quick turn-around times. Part of the cost reduction is that direct-write e-beam lithography does not require a set of photolithographic masks, which become increasingly expensive as the feature sizes get smaller. Some important applications often require small numbers of wafers and devices, whether they be microelectronic, MEMS, NEMS, photonic, etc., or some combination therein, and it is frequently cost prohibitive to produce these devices using the most advanced photolithographic technologies in extremely small batch sizes because the amortization costs of the photolithographic mask set can only be spread over a relatively small number of wafers. Moreover, a multiple e-beam direct-write lithography tool can be installed in a foundry to enable affordable production of small lots of state-of-the-art nanosystems for a broad spectrum of existing and emerging applications. Additionally, it is expected that a multiple e-beam direct-write lithography tool technology will also find wide application in the commercial sector for nanopatterning masks for DUV lithography and templates for imprint lithography, thus defraying enormous tool infrastructure costs.